Oil-cooled stators for turboalternators



M. SEIDNER March 14, 1961 OIL-COOLED STATORS FOR TURBO-ALTERNATORS Filed May 5. 1959 INVENTOR. M\HALY SEIDRER OlL-COOLED STAT ORS FOR TURBO- ALTERNATORS Mihaly Seidner, Budapest, Hungary, assignor to Komplex Nagyberendezsek Export-Import Vallalat, Budapest, Hungary This invention relates to oil-cooled stators for turboalternators, having a laminated stator body with a jacket and an axial bore, axial grooves in the surface of said bore, conductors in said grooves, a closing pipe concentrically disposed in said bore and limiting it in radial direction for receiving a rotor, head members connected to the extremities of said stator body and enclosing chambers with the front ends of said stator body and said closing pipe, and insulated windings consisting of said conductors within said grooves and of head portions accommodated in said chambers.

As is known, the chambers enclosing the head portions of the windings of such type of stators are filled with oil. Obviously, the space required by the head portions of the winding and, thereby, the amount of oil required for filling empty portions of said space increase with the square of the diameter of the bore provide in the stator body for receiving the rotor of a turbo-alternator, an elevation of the capacity of which necessitates, in turn, an increase of said diameter. Thus, in case of turboalternators of elevated capacity the amount of oil required for filling up the chambers for the head portions of the stator windings is a multiple of the amount required for the cooling of such portions. Moreover, in case of serious short circuits in the head portions of the windings gas formation is augmented by the excess oil in the chambers, as is well known with oil-immersed transformers.

The main object of the present invention is to obviate the above said difliculties. For this purpose, the chambers, so far they are not occupied by the head portions of the windings, are filled up by insulation material. Accordingly, the invention consists in an oil-cooled stator for turbo-alternators of the above described type wherein the space within the head members left free by the head portions is, in accordance with the main feature of the invention, filled up at least partly by bodies made of insulation or dielectric material. Thus, the required volume of oil is restricted to a fraction of the volume of the free portions of the space within the chambers and the presence of such excess oil is eliminated. Furthermore, in case of short circuits, a formation of gas is possible only upon oil dripping.

Further objects and details of the invention will be described with reference to the accompanying drawings which show, by way of example, a preferred embodiment of an oil-cooled stator for turbo-alternators according to the invention. In the drawings:

Fig. 1 is a front elevation view of the stator of a turbo-alternator partly in section.

Fig. 2 is a diametric cross-sectional view taken along the line 11-11 of Fig. 1.

Fig. 3 is a detail of Fig. 2 on a larger scale.

In the drawing, 10 designates a laminated stator body which has an axial bore 11 for receiving a rotor (not shown). In radial direction the bore 11 is limited by a closing pipe 12 disposed concentrically within said bore 11. The windings of the stator 10 consist of hollow tes Patent Patented Mar. 14, 1961 conductors 14 having cooling passages 13. The head portions 14a, 14b of the windings are disposed in chambers enclosed by the closing pipe 12 and by head members 16a and 1612 connected to the front sides 15a and 15b, respectively, of a finned jacket 15 of the stator body 10, said closing pipe 12 being supported by said head members 16a and 16b. Portions of said chambers left free by the head portions 14a and 14b, respectively, of the stator windings are filled up partly or, as in the instant case, wholly by bodies made of insulation material such as a plastic as suggested by reference characters 17a, 17b and 18a, 1812, respectively.

The stator as a whole is provided with a pair of independent systems of cooling passages in a manner known per se. One system consists of the conductors 14 accommodated in grooves 20 of the stator body 10. The cooling passages 13 of the conductors 14 are supplied by a cooling medium such as oil through a. nipple 23a communicating with an annular chamber within the head portion 16a. The cooling medium exits through an annular chamber 19b within the head member 16!; and through a nipple 23b connected thereto. The other system of cooling passages is formed by axial channels 22 provided in teeth 21 of the stator body 10 which enclose the grooves 20 receiving the conductors 14. Both the passages 22 and the passages 24 communicate with collecting chambers 25 and 26, respectively, within the jacket 15 at the extremities of the stator body 10. The collecting chambers communicate with nipples 27 and 28 for the introduction and withdrawal, respectively, of the cooling medium, e.g. oil.

It will be seen that the windings are submerged in oil along their entire length. Thus, their insulation may be made of paper instead of expensive mica as is usual with oil-immersed transformers. Apart from decreasing the required amount of oil this is obviously a further advantageous feature of the invention.

In the above description the term oil designates all natural or synthetic fluids suitable for cooling of transformers.

What I claim is:

1. An oil-cooled stator for dynamo electric apparatus comprising, in combination, a laminated stator body having an axial bore and formed with circumferentially spaced axial grooves in its radially inner surface opening into said bore; an outer jacket enclosing said stator body; hollow head members connected to the axially opposite ends of said jacket; a self-supporting closing pipe seated in said bore and closing said grooves and the radially inner ends of said head members, whereby said head members and said closing pipe define a pair of chambers; insulated windings consisting of hollow conductors disposed within said axial grooves and of hollow head portions in communication with said hollow conductors and disposed in said chambers; nipples communicating with said chamber for flow of cooling fluid into one chamber and from the other chamber; and bodies of dielectric material filling said chambers and surrounding said head portions, said bodies defining relatively small area passage means connecting the interior of said head portions to the respective nipples.

2. An oil-cooled stator for dynamo electric apparatus as claimed in claim 1 in which said windings are insulated with paper.

References Cited in the file of this patent UNITED STATES PATENTS 2,390,130 Sigmund Dec. 4, 1945 2,462,451 .Winther Feb. 22, 1949 2,829,288 Schaefer Apr. 1, 1958 

